1. The Field of the Invention
The present invention is generally related to optical transceivers used in fiber optic communications systems. More particularly, the present invention provides for a transceiver design and manufacturing process that allow for the passive alignment of an optical emitting component with a lens.
2. The Relevant Technology
Because of their high bandwidth and reliable high-speed data transmissions, fiber optic networks are increasingly becoming a popular mode of communication. These high-speed communication networks utilize optical-electronic components such as optical transceivers in transmitting information via the network from a transmission node to a reception node. An optical transceiver at the transmission node receives an electrical signal from a network device, such as a computer, and converts the electrical signal via a laser to an optical signal. The optical signal can then be emitted by a transceiver and transmitted in a fiber optical cable via the optical network, such as a local area network (LAN) backbone, for instance. The optical signal is then received by a reception node of the network. Once received by the reception node, the optical signal is fed to another optical transceiver for conversion via a photo-detector into electrical signals. The electrical signals are then forwarded to a host, such as a computer, for processing. The optical transceivers described above have both signal transmission and reception capabilities; thus, the transmitter portion of the transceiver converts an incoming electrical signal into an optical signal, whereas the receiver portion of the transceiver converts an incoming optical signal into an electrical signal.
Due to the power requirements and optical properties associated with the transfer of light to and from the transceiver to the optical fibers, transceivers should be fabricated with a high degree of accuracy. Accordingly, the active components (e.g., the laser and photo-detector) should typically be aligned within sub-micron accuracy with their respective lenses and optical fibers. Such precision alignment and fabrication is usually actively or manually performed by skilled technicians working with microscopes and high-precision manipulators. Once each optical device is assembled, it may be powered up and tested to verify proper performance and adjustments may be manually made as needed.
The laser and photo-detector typically resided on separate substrates disposed in a transmitter optical assembly (“TOSA”) and receiver optical subassembly (“ROSA”), respectively. Accordingly, the alignment of the laser and photo-detector within a transceiver would take place separately, wherein one component, then the other, is aligned. Modem advancements, however, have simplified transceiver designs by including a single substrate structure that houses the active optical components for both the transmission and reception of optical signals. The singular substrate housing is attached to a duplex sleeve assembly that provides ports to which connectorized fiber optic cables are attached.
Although the unification of the TOSA and ROSA to produce a single transmitter/receiver optical assembly (“TROSA”) has simplified transceiver design, the unification has increased the stringent requirements for aligning the active components to the respective lenses and fiber optics. For example, because the active components reside on a single substrate they must now be aligned with respect to one another, within micron tolerances. Similarly, the respective lenses within the duplex port assembly must be aligned with respect to one another, and then with respect to the active components when the substrate housing is attached to duplex port assembly. With the added degrees of alignment, as well as the constraints imposed by a single subassembly process (i.e., the attachment of the single substrate housing the active components with the duplex port assembly), the cost in aligning the appropriate components of a transceiver has dramatically increased.